An investigation of the effect of inducing molecular alignment on the lubrication performance of 5CB liquid crystal

• Published in: Tribology international Vol. 197; p. 109823
• Main Authors: Sun, Qilin, Chen, Hui, Xiao, Guangchun, Yi, Mingdong, Zhang, Jingjie, Chen, Zhaoqiang, Xu, Chonghai
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2024
• Subjects: Alignment; Liquid crystal; Lubrication performance; Running-in-deflection; Running-in-deflection; Alignment; Liquid crystal; Lubrication performance
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2024.109823

The lubrication alignment behaviors of 4-Cyano-4′-pentylbiphenyl (5CB) liquid crystal were investigated. A 60 s-long running-in pre-treatment was first performed using micro-sized diamonds. The ball was then deflected by a certain direction and an alignment agent (Sebacic Acid) was applied on the disc. Results show that the coefficients of friction for GCr15 and Si3N4 self-matching pairs were reduced to 0.036 and 0.017 respectively, 45.5 % and 67.3 % lower than the ones lubricated directly with 5CB. The surface morphology after running-in-deflection was smoother and flatter, with enhanced surface texture characteristics. It is believed that increased the order parameter of 5CB, induced by the synergistic effect of the alignment agent and running-in-deflection, is the reasons for the improvement in lubricating performance. [Display omitted] •The alignment agent and running-in-deflection reduce the COF of 5CB notably.•The reduction of COF is attributed to the liquid crystal molecular orientation.•An appropriate running-in-deflection is beneficial to reduce the COF of 5CB.•The relationship between surface parameters and characteristics has been analyzed.